Tool.



CHARLES PALMGREN, OF CHICAGO, ILLINOIS.

` rrooL.

Specification of Letters Patent.

Patented Nov. i9, 1918.

. Application filed October 11, 1916, Serial No..1\2`5,068.

To all whom t may concern.'

Be it known that I, CHARLES A. PALM- 'GREN, a citizen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Tools, of which the following is a specification, reference being had to the accompanying drawings.

My invention relates to cutting and boring tools and particularly to those designed for working in metal, although it may be applied to tools used for working on other materials. It has for its object to provide a new and improved milling tool for cut ting an annular channel about a predetermined axis in a block or billet of steel preparatory to using a hollow drill in such channel to form an elongated core which may subsequently be removed for purposes of analysis. In the steel industry, steel required for use in many lines of manufacture Y. must come up to certain specified standards,`

and in order to ascertain the `suitability of the steel for the uses to which it is to be put, it is customary to make frequent tests of the quality of the steel. For the purpose of making'these tests, it iscustomary to remove samples of different parts of a mass or billet ofsteel, and among other ways of obtaining the desired samples it has been proposed to bore into the steel billet by meansof a hollow drill 'so'as to form a cylindrical core which maybe afterward removed and tested or analyzed. As such masses of steel usually have rough or. un finished surfaces and the sample to be obtained must be taken at the' point indicated by the inspector, it is frequently very difficult to bore at the point indicated, owing to the factA that the roughness of the surface interferes with starting the drill. To provide a suitable starting place yfor the drill, it has been proposed to employ a hollow end mill to cut an annular channel rof the proper size to receive the hollow rdrill subsequently used, but'such hollow end mills as hereto--` fore constructed have not been much better axis of the core to be cut, because, owing to the roughness ofthe surface operated upon, the yengagement of the teeth of the mill with the roughnesses of such surface, and the fact that the centering pin is necessarily yieldingly projected by spring pressure, the mill would shift from its initial position` and the bore would not be made with the necessary accuracy. Consequently .such mills have not been successfuhandso far as I am aware, no satisfactory tool for the purpose has been produced prior to that which forms the subject-matter of this application. The latter overcomes all the objections to prior devices of the kind, and fully meets all the requirements of the work foi which ,it is designed.

My improved tool comprises a head having a suitable shank by which it may be mounted in a drill press, or other suitable machine, and rotated at a suitable speed. At the outer or operating face of the head are provided a plurality of cutting teeth arranged equidistant from the axis of the head, the head being bored centrally so that such teeth are adapted to cut an annular channel. mounted a pointed centering pin, which is resiliently projected beyond the operating face of the head by a spring mounted in the head back of the pin and disposed around the stem thereof. y The parts thus far described are not new. My invention consists in providing a Ytool such as that described with supplementary means for holding the head lin position to maintain the concentricity of the channel cut by the teeth with a predetermined axis, such means consisting of supplementary teeth which are carried by the cutting teeth before mentioned and project a shortdistance beyond the same. Such supplementary teeth are also equidistant from the axis of the head, and consequently by reason of the fact that they project beyond the cutting edges of the main teeth, they engage the material to be drilled first and act to cut an annular channel therein which is concentric with the predetermined axis of the core to be cut. These supplementary teeth are best made V-shape incrosssection, as the teeth may in that way be made stronger, and the channel cut by them is of corresponding shape in crosssection. When lthe tool isused, the centering pin is, of course, forced back into its socket until it projects only as far as the points of the In the central bore of the head isv supplementary teeth, so that when the tool is applied to the mass of steel to be bored the supplementary teeth rst cut the supplementary channel, and as the tool enters they material, the main cutting teeth nally come into operation and cut. lthe main channel which is to receive the hollow drill by which the core is formed. The axis ofthe core to be cut is marked by a center punch in the usual way, and `the centering pin is then placed at that point. Consequently, when the tool is rotated, the supplementary teeth coperate with the centering pin to hold the tool properly in position, since the supplementary channel keeps vthe tool from slipping sidewise while the main teeth are biting depressionforrned by the center punch.

Referring now to the drawings for a more particular' description of the embodiment of myinvention'therein illustrated, 5 indicates the head of the tool, and 6 its stem -or shank Aby which it is mounted in a drill press orother suitable machine. YAs best shown in Fig. 2, the head 5 is provided vwith a longitudinally-extending central recess 7, the in-4 ner portion of which is of' reduced diameter, as lshown at 8 lin Fig. 2,l forming apshoulder 9.v Mounted'in this recess is a cen-- tering pin 10 having a pointed end 11 and a stem 12 which extends into the 'reduced portion 8 of the recess, its inner end being provided with a collar 13. 13a indicates a' stop which limits the outward movement of the centering pin by its engagement with the collar 13. 14 indicates a spring mounted on the stem 12 and bearing against the shoulder 9 at one end and against the body of the pin 10 at the other end so that it tends to' project the point beyond the operating face of the tool. Arranged around the ypinv 10 are main cutting teeth 15, preferably four `1n number, as shown in Figs. 1 and 3, the cutting edges of the teeth being at the-end of' the tool. 16 indicates auxiliary teeth, preferably triangular in cross-section, which are mounted upon the cutting faces of the main teeth 15 and 'project therefrom, as shown in the drawings. These auxiliary or supplementary teeth are preferably disposed cen'- trally of the main teeth, and their function is to preliminarily cut a vchannel in' the materiall operated lupon which will cooperate with the pin 10 to hold the tool against lateral deflection due to the roughness ofthe surface operated upon. The op- .I eration has already been described, but itv may be well to state again that the point to befboredis first marked by a center punch, after which the tool is applied, the point of the centering pin,10 being placed in the placeso marked. The tool isthen pressed down upon the material so that the center-- ing pin is forced back into its recess and the supplementary teeth 16 permitted to come inpcontact with the material .to be bored. As the tool rotates, the supplementary 4teeth cut into the material, forming an annular groove in which` they quickly embed themselves, so that then the tool is heldagainst lateral deiection not only by the centeringr pin but also by the supplementary. teeth. The main teeth then come into action andA cut themain channel. The inal'result is shown in Fig. 4, in which'17 indicates the point marked by the center punch, 18 the channel cut by the supplementary teeth, and 19 the main channel. An ordinary hollow drill may then be yapplied andthe core formed, as indicated by the dotted lines in Fig. 4. i A v f That which I clai asv my invention, and desire to secure by Letters Patent, is

1. A tool, comprising a head having a centering pin, a plurality of teethadapted to cut an annular channel `as the tool is rotated, and supplementary means carried by and projecting beyond said teeth.- for holding said head in position to maintain the concentricity of such channel with a predetermined axis. f U l k2. Atool, comprisingv a head having acentering pin, a plurality of cutting teeth adapted to cut an annular lchannel as the tool is rotated, and supplementary teeth carried by and .projecting beyond said teeth for holding-said head in position tol main-. tain the veoncentricity of such channel with a predetermined axis. f

3. A tool, comprising a head having a centering pin, a plurality'of teeth adapted to cut an annular channel as the tool is rotated, and V-shaped supplementaryr teeth mounted on and projecting beyond the firstmentioned teeth for holding saidl head in position to maintain the' concentricity ofsuch channel with a predeterminedaxis. j

4. A tool, comprising a head having a central bore, aL plurality of cutting teeth adapted to cut an annular channel as the tool is rotated, and supplementary-teeth carried by and projecting beyond said'fcutting teeth lfor holdingsaid head in position to maintain the concentricity of such channel with a predetermined axis. f

CHARLES A.. PALMGR-EN. j

Copies of this patent may be obtained for five cents each, byi addressing thelcoknnvnissicner fjatents Washington, D. Q. 

